Fluid machines such as compressors are typically lubricated by oil drawn from a sump by a pumping structure associated with the crankshaft. Centrifugal pumps and positive displacement pumps such as gerotors are commonly used to pump the oil. One problem associated with reciprocating compressors and rotary compressors such as scroll compressors is that they can run in reverse due to miswiring, and 3-phase operation can be in either direction. Also, some rotary compressors can run in reverse due to a pressure equalization across the compressor upon shut down. Under these conditions some types of oil pumps do not function properly and damage can result from lack of adequate lubrication. Those oil pumps that do function properly under reverse rotation conditions are, typically, relatively complicated and costly.